1. Field of the Invention
The invention relates to a photosensitive resin composition for a color filter in a liquid crystal display element, and a color filter and liquid crystal display element formed by the aforementioned photosensitive resin composition. More particularly, the invention provides a photosensitive resin composition for a color filter having good voltage holding ratio, and good developing-resistance.
2. Description of the Related Art
Currently, a color filter has been applied widely in the field such as a color liquid crystal display device, a color fax machine, a color camera or the like. Since the requirement of imaging equipment, such as color liquid crystal display device, has become expanding, the production technology of the color filter also tends to diversify.
The color filter is usually obtained by a dyeing method, a printing method, a plating method, a dispersion method or the like, wherein a red pixel, a green pixel, and a blue pixel are formed on a transparent glass substrate. Generally, in order to raise the contrast of the color filter, a black matrix is usually disposed between the colored pixel layer.
The process of the aforementioned dispersion method comprises, first, dispersing pigments in a photo-curing resin to form a colored photosensitive resin composition, and then forming a colored pixel layer with the resin composition. Furthermore, the process of the dispersion method usually comprises using a metal such as chrome or chrome oxide or a photosensitive resin shading film to form a black matrix on a transparent support such as a glass substrate, and coating a photosensitive resin dispersed with a red pigment (also referred as color photoresist) on the transparent support by spin coating. After the steps of exposure and development, a red pixel can be obtained. Such process is repeated, and a green and blue pixel can be obtained thereby.
In recent years, the application of the color liquid crystal display device is not limited in personal computers, and it has been applied widely in color televisions and various monitor screens (particular in color liquid crystal screen of large sizes), so the requirement for color saturation of the liquid crystal display device becomes higher. Due to the requirement of the high color saturation, it needs to increase the concentration of pigment, and under the high-concentration pigment, the ratio of the pigment in the photosensitive resin composition is also high which leads the relative used amount of the alkali-soluble resin and photosensitive monomer to decrease. Such phenomenon causes the decrease of the degree of cross-linking after exposure and then causes poor develop-resistance.
Japanese Patent Publication No. 2004-138950 discloses a specific alkali-soluble resin for forming a colored pixel layer with a flat surface and a color filter having good pattern, developing-resistance and brightness. However, the voltage holding ratio of the photosensitive resin composition too is too low and it leads image sticking in display.
Therefore, improving the voltage holding ratio and the developing-resistance simultaneously in order to meet the modern requirements is a target remained to be achieved.